The present invention relates to a control circuit and a method for qualifying a fault for a synchronous machine, in particular a permanently excited synchronous machine or an electrically excited synchronous machine.
The knowledge of the rotor position angle is necessary to control permanently excited synchronous machines and electrically excited synchronous machines, as said machines are, for example, used in hybrid and electric vehicles. This is also denoted in short as the rotor angle and bears the mathematical symbol φel. In order to determine the rotor position angle, different types of sensors are known, for example digital angle sensors, resolvers or sensors on the basis of the eddy current effect.
In order to monitor the function of such sensors, diagnostic signals are typically generated, wherein a fault is indicated when a predetermined diagnostic threshold is exceeded. As a result, short-term outliers can occur, i.e. irrelevant peaks in the diagnostic signal. In order to prevent an erroneous qualification of a fault, diagnostic signals are conventionally temporally, i.e. on a time basis, debounced. During the time-based debouncing, a fault is qualified, i.e. an actual fault is recognized, if the diagnostic signal lay without interruption above a diagnostic threshold. Diagnostic signals are also called diagnostic comparison signals.
In the European patent application EP 1004474, a method and a circuit arrangement for comparing an input signal with different voltage thresholds in an electronic flasher unit are described, wherein a temporal debouncing of an output signal is carried out.